Low thyroid. 7 weeks

Larissa
Results for my lab came back today with me having low thyroid, I asked for labs because my exhaustion was so excessive even for 1st trimester. 
My appointments not for 3 weeks and the nurse wasn't very informative. 
Anybody else deal with this? What effect can it have on pregnancy, baby/fetus, delivery, ect...?
How concerned should I be?